Introduction - Human-Computer Interaction - page 14

cussed above, this comprises for instance the way how documents are marked up
during reading and the way how collections of documents are organized. It is there-
fore crucial that digital support is capable of adapting to these personal practices,
preferences and habits. A further challenge is connected to the high degree of cogni-
tive load [15] which characterizes many situations of knowledge work. For instance,
reading and understanding complicated subjects matters are cognitively demanding
tasks. It might be by no means a simple coincidence that traditional tools and inter-
actions for working with documents are characterized by a high degree of simplicity
and intuitiveness. Like traditional tools, novel interactions should produce little ex-
traneous load in order to be easily integrated into existing practices.
Collaboration Support As the analysis of the affordances of paper has shown,
paper is a collaborative medium. Using paper is very powerful during co-located
interaction because its physical nature affords flexible multi-user interaction in co-
presence. For example, it is very easy to jointly write on a document. Documents can
also be flexibly moved and spatially organized to structure them or to (re-)attribute
specific documents to specific persons. However, it is cumbersome to use paper for
collaboration over distance. PPUIs offer a benefit here, since interactions with phys-
ical documents can be electronically tracked. The question is what are appropriate
interactions and visualizations to support paper-based collaboration over a distance.
1.4 Contributions and Structure of this topic
This topic is a substantially revised and extended version of the author's doctoral
dissertation. As outlined above, our overarching goal is to provide answers to the
question of how to design user interfaces that effectively integrate traditional pen-
and-paper-based practices with digital documents. Our application domain is knowl-
edge work and we particularly focus on knowledge acquisition tasks. We take on
an integrated viewpoint that takes into account the various activities that are cen-
tral to knowledge work. The scientific contributions that are discussed in this topic
are situated in the fields of interaction theory, interaction techniques and interac-
tive systems. They comprise a comprehensive survey of related work (Chapter 2), a
theoretical interaction model (Chapter 3), and a set of novel interaction techniques
which instantiate the model (Chapters 4-7).
Chapter 2 provides an extensive survey of prior research that has been conducted
in the field of Pen-and-Paper User Interfaces. It discusses technologies which enable
to build bridges between paper documents and the digital realm. Moreover, it gives
an overview of technical frameworks that support developing end-user applications
with pen and paper. Furthermore, it discusses existing interactive paper systems,
interaction concepts and applications.
Chapter 3 introduces a theoretical model of Pen-and-Paper User Interfaces (PPUIs).
Prior research in this field has focused on systems and not on theory. The model